Coursework is marked 'internally' (not by the exam board, but by your teacher or equivalent) so you would either need to register for the exam through your school (they usually let you do this for a fee) so that a teacher can mark it, or find an exam board that doesn't require coursework.
If you are resisting your exam, you have to resit ALL the components (at least for reformed A-levels), which would mean redoing your coursework and having it remarked.